1. Field of the Invention
The invention relates to an adaptor, more particularly to an adaptor with electromagnetic shielding capabilities.
2. Description of the Related Art
The need to minimize the effects of electromagnetic interference grows in importance as the complexity and precision of electronic equipments increase. Since it is not uncommon to transmit and amplify weak signals in multiple stages, interference in the original signals may exceed tolerable levels during the final stage. Presently, several filter and amplifier stages are employed to minimize the effects of signal interference during signal transmission. Such a solution increases the costs incurred and does not necessarily provide ideal results.
Referring to FIG. 1, a conventional adaptor is shown to comprise a circuit board 10, a DIP switch unit 101 provided on the circuit board 10, and an adaptor casing which includes lower and upper casing halves 11, 12 that are made of plastic. The upper casing half 12 is formed with an opening 121 that is aligned with the switch unit 101, thereby enabling the latter to extend out of the adaptor casing to facilitate operation thereof. The lower and upper casing halves 11, 12 are joined together so as to enclose the circuit board 10 therein.
As the requirement for purity of signals becomes more stringent, the density and complexity of the adaptor circuit similarly increase. The presence of the switch unit 101 enables the adaptor to operate in different signal conversion modes. However, due to the complexity of the adaptor circuit, which results in a longer transit time for signals, and the presence of multiple contacts at the switch unit 101, signal interference is likely to occur since the plastic adaptor casing only serves to protect the circuit board 10 and does not serve to minimize the presence of electromagnetic interference.